Orchard heater



J. H. MGCRACKEN 4 ,3

ORCHARD HEATER Filed'Dec. 4, 1940 2 Sheets-Sheet l //v l/[N TOR John hf Ma Crackefl Ar/omeg Aug. 29, 1944.

'J. H. M CRACKEN ORCHARD HEATER Filed Dec. .4, 1940 2 Sheets-Sheet 2' c/0/7/7 H Ma Cracks/7 Patented Aug. 29, 1944 ORCHARD HEATER John H. McCracken, Oakland, Calif., assignor to California Fruit Growers Exchange, Los

Angeles, Calif., a corporation of California Application December 4, 1940, Serial No. 368,467 I,

' Claims. c1. 158-91) This invention relates to an orchard heater and more particularly to the drip type of orchard heater.

The principal objects of this invention are to provide an orchard heater of this type in which the surface area of the oil exposed to volatilization increases approximately proportionally to the increased flow of oil into the heater, which is adapted to burn the ordinary orchard heater fuel over a wide range, and at relatively high burning rate, without producing objectionable quantities of smoke, and in which very little soot or carbon is deposited in the heater as a result of the combustion of the fuel; which heater is simple in construction and readily adapted to be dismantled for purposes of cleaning, and need not necessarily be maintained level for purposes of efficient operation.

These and other objects, uses, and advantages and adaptations of the invention will appear more fully and at large hereinafter, and will be apparent to those skilled in the art.

Frost prevention practices with respect to orchards, and more particularly citrus orchards,

have undergone many changes during past years.

Of the several means now in use for protecting fruit and trees from frost damage, probably the most common and effective practice involves the use of individual heaters placed among the trees.

Although there are heaters used which are adapted to burn various fuels, the large majority of the heaters now in use burn an oil of the marine Diesel type. These heaters may be classified into four general types: distilling, atomizing, generating, and drip type.

The drip heater gets its name from its mode of operation. In these heaters the oil is supplied to the heater, or, more particularly, to the vaporizing element of the heater in the form of a dripping stream. The oil usually falls 'on a hot surface where it is quickly volatilized and ignited.

Although these heaters present some very definite advantages over the other types of heaters, their extensive use has been hindered by the fact that, for the most part, they could not be made to operate satisfactorily with the grade of fuel used in the other types of heaters. Whereas a distilling type of heater will operate on fuel oil of the marine diesel type having a gravity of 27+ A. P. 1., the drip heaters heretofore available have usually required a fuel having a gravity of 34 A. P. I. or better. Also, the ordinary drip heater has a limited burning rate, that is to say, the heaters are designed to burn fuel at a rate of from about 0.4 to 0.7 gallon per hour and When operated above this rate they tend to produce more smoke than is legally allowable. Furthermore, it has heretofore been particularly necessary to maintain the drip-type heaters in a level position in order to obtain satisfactory operation. Since many groves are set on hillsides, and since the orchards usually are furrowed, the orchardist finds it extremely diflicult to'use a drip-type heater which must be maintained level.

The importance of my invention, therefore, lies in the fact that I have produced a drip heater which eliminates the objectionable features mentioned hereinabove, while at the same time giving a highly satisfactory operation in a variety of positions and over a wide range of burning rates.

In the drawings:

Fig. 1 is a side elevation of the heater, showing the stack in place on the heater body.

Fig. 2 is a plan view of the heater body taken along the lines 2-2 of Fig. 1.

Fig. 3 is a vertical, cross-sectional view of the heater body taken along the line 3-3 of Fig. 2.

Fig. 4 is a vertical, cross-sectional view of the heater body taken along the line 4--4 of Fig. 3.

Fig. 5 is a detail View showing the port control mechanism. I

Fig. 6 is a vertical, cross-sectional view taken along the line 66 of Fig. 5, and shows details of the wick and port control mechanism.

Fig. '7 is a plan view of the open vaporizer.

Fig. 8 is an elevation of the open vaporizer.

Referring now to the drawings in detail, it will be apparent that the embodiment of the invention which has been illustrated comprises a heater body 20, provided with a bottom aperture 2| and neck 22.. The heater body is supported on legs 23. Suitably attached to the outside of the heater body is a fuel pipe brace 24 supporting a fuel pipe 25. The fuel pipe 25 is provided with a collar 26 to prevent run-back of the fuel along the outside surface of the fuel pipe. Over the neck 22 of the heater body there is fitted an inverted, frusto-conical section 21, having a straight portion 28. This section has louvers 29 around its upper periphery. Over the inverted, frusto-conical section 21 there is fitted, as by means of a slip joint, an upright frusto-conical section '30 having louvers 3| around its middle periphery. Within the heater body 20 and suitably supported by the double arm brackets 32 and 33 and single arm brackets 34 and 35, is an open helical vaporizer 36 having depending lips 31 and 38. A series of baflies 39 is formed in the bottom of the open vaporizer. Also within the heater body and suitably fastened to the bottom thereof is a wick 40 comprising some absorbent, non-inflammable material such as glass wool or asbestos fiber, said material being held in position by an L-shaped plate 4|, the shorter side of the plate being parallel to the side of the heater body and opposite a port 42 positioned in the side of the heater body a short distance above the wick. The port 42 is adapted to be partially closed by a gate 43 which cooperates in thisrespect with the upwardly extending arm of the L-shaped plate 4|, said gate 43 being attached to a thermo-metal or bimetallic strip 44 which is fastened to the side of the heater body above the port 42.

In constructing the particular embodiment of my invention from which the illustrations used in the drawing have been taken, the following approximate dimensions and proportions were used:

The heater body 20 is 12 inches in diameter and its main portion is 8 inches deep. The bottom should be about 3 inches above the ground. The bottom aperture 2| is 2 inches in diameter and its lip is turned up inch above the bottom of the heater body. The collar or neck 22 is 8 inches in diameter and 1 inches high.

The stack is 24 inches high, and the belly is slightly below mid-point of the height. The diameter of the bottom is 8 inches, at the belly 12 inchesyand at the top '7 inches. There are 18 louvers 1 inch below the belly, which are inch wide and /8 inch deep. There are 14 louvers 6 inches below the top and they are /2 inch wide and inch deep.

The open helical vaporizer shown describes 1 turns and is set so that it eXtends back 4 turn behind the fuel pipe, to catch the run-back, at least in-part, if the heater is tipped. At the point where the oil normally falls upon it, the bottom of the vaporizer is 6 inches above the bottom of the heater body. The vaporizer shown is about 1 inch in diameter and forms a coil about 8 inches in outside diameter. The baffles are about 1% inches apart and rise 4 inch above the bottom of the vaporizer. Tangents of the coil form an angle of about 10 with the horizontal, so that it drops about 2 /2 inches in one turn.

In speaking of the vaporizer as being an open vaporizer, I do not refer merely to the fact that the vaporizer is open at the top, but also to the fact that the vaporizer is so constructed as to be open or exposed to the heat of combustion occurring within and upwards of the neck 22 and in the heater stack, and this exposure is entirely unimpeded by any central obstructions. It will be apparent from what has been said and from'an inspection of the drawings that the open vaporizer will see-that is to say, will be directly exposed to radiant heat fromthe entire neck at all points in the first complete turn of the vaporizer and that even in the lower half turn it will at all points see a major portion of the area of the neck 22. Since the flaming occurs within and upward from the neck 22, the vaporizer is thus maintained at adequate temperatures for volatilization of the fuel.

By positioning the bottom aperture in the manner shown, and in relation to the vaporizer as shown, free access of primary air to the vaporizer is provided.

'In use the stack sections 27 and 30 are assembled on the heater body as shown in Fig. 1. Oil

is then admitted to the heater through the fuel line 25 at a proper rate. Inside of the heater body the oil drips from the collar 26 onto the open helical vaporizer 36 and flows over the series of bafiies 39, and may finally drip off the depending lip 38 onto the wick 40, if not previously consumed. As soon as the fuel has been admitted to the vaporizer, the heater is ready to be lighted.

The usual lighter-fluid is poured from a lighted torch into the heater through the top of the stack so that the lighter-fluid falls into the heater body. Any fluid falling on the open vaporizer will flow in part to the wick below. Since the lighter-fluid coming from the torch is burning as it falls into the heater body 20 and onto the open vaporizer 36 and wick 40, the film of oil flowing over the vaporizer and any oil absorbed on the wick is readily vaporized by the heat from the lighter-fluid and is quickly ignited. I find that suflicient lighter-fluid is absorbed on the wick to maintain a flame thereon for a time suflicient to assure vaporization and ignition of the fuel flowing over the open vaporizer 36 so at the outset burning takes place on the Wick, as well as along the surface of the vaporizer. Burning continues at these points until the body of the heater and the open vaporizer have become sufliciently heated to volatilize the oil flowing from the fuel pipe 25 onto the open vaporizer 36. When the heater body and vaporizer have become thus sufliciently heated, the thermo-metal or bimetallic strip 34 is expanded away from the heater body 20. This in turn moves the gate 43 away from the upwardly extending arm of the L-shaped plate 4| and fully opens the port 42, through which air is admitted with suflicient force to. extinguish the flame on the wick. In particular, it is pointed out that the gate in its first position is in alinement with the port 42, and thereby guides the inflowing air away from the flame on the wick. Theheat responsive operating means when in action, moves the gate 43 into a position which permits the air to flow directly over the wick to extinguish the flame thereon. The inflow of primary air through the bottom aperture 2| has free access to the open helical vaporizer and mixes with the volatilized fuel. As the heater body warms up the flow of air through the bottom aperture 2| increases and forces the flame outside of the heater body 20 and into the stack. Burning of the vaporized fluid, therefore, takes place outside of the heater body and inside and above the stack. As a consequence, deposition of soot in the heater body is avoided.

The heater is extinguished by shutting off the fuel supply.

It is desired to point out in particular some of the advantages of my heater. In the first place, the stack sections 21 and 30 have been constructed so as to increase the combustion of gases and reduce the amount of smoke liberated by the heater. To accomplish this, I have constructed a stack which has a considerable bulge around its middle. This in itself, however is not suflicient to materiall increase the combustion of gases and reduce the amount of smoke, but by placing a row of louvers, indicated at 29 in Fig. 1, around the upper periphery of the stack section 21, which when the stack is completely assembled on the heater body places this row or louvers 29 somewhat below the maximum bulge of the assembled stack, I accomplish two very important results. In the first place, the row of louvers 29 admits secondary air to the heater at a point where the burning of the vaporized fuel is taking place and, therefore, prevents overheating of the stack at this point. Secondly, and,

I believe, of greater importance, this row of 1011- vers assists in reducing the amount of accumulated soot in the upright frusto-conical section 30 by assuring a more complete combustion of the gases andof the carbon particles. Also, the more complete combustion of carbon particles is further facilitated by the row of louvers 3| positioned in the upright frusto-conical section 30.

Another very important advantage of my heater lies in the fact that it is not necessary for the heater to be maintained level in order to operate efliciently. The open helical vaporizer has been constructed and assembled so that it will receive the oil from the fuel pipe regardless t whether or not the heater body is level. This result is achieved by placing the vaporizer in such relationship to the fuel pipe that an ample length of the vaporizer trough extends back and upward from the fuel pipe so that even though the heater body is not level, the fuel will continue to fall onto the vaporizer and flow downward over the bafiles. As a further precaution against the oil dripping other than on the vaporizer, the depending lip 31 is positioned directly above the channel of the lower turn of the vaporizer so that any oil flowing over the end of this lip will fall into the trough of the vaporizer directly underneath.

Referring in particular to the open vaporizer itself, it will be noted that I have formed a series of baffles in the channel of the vaporizer. These baffles retard the flow of oil over the surface of the vaporizer and, more particularly, increase the surface area of the vaporizer. By increasing the surface area, a thinner film of oil is subjected to heat and, consequently, becomes volatilized much more rapidly than the same amount of oil confined to a lesser area and greater depth.

Although orchard heaters are usually operated at a relatively low burning rate, during periods of intense cold the heaters throughout an area are operated at or near their maximum burning rate, which results in an increase in the smoke output far beyond the legal limits. With my heater, however, this is not the case, since, as mentioned before, the smoke output of the heater is very low over a wide burning range and apparently even decreases with the increase in the burning rate, up at least to 1% gallons per hour.

In addition to the features mentioned above, attention is directed to the fact that my heater has a much wider burning rate range than the usual heaters of this type; for example, whereas the burning rate range of the ordinary heater of this type is from about 0.4 to perhaps 0.7 gallon per hour, I am able to obtain satisfactory and efficient burning over a range of from 0.4 to about 125 gallons per hour. I attribute these advan tages and unusual results to the type and placement of the vaporizer with respect to the inlet aperture for the primary air and to the stack assemblage and arrangement of louvers thereon.

It is to be presumed that variations and modifications will occur to those skilled in the art with respect to this invention. Any and all changes, modifications, and alterations coming within the scope of the appended claims are to be considered as embraced thereby.

Having thus fully described m invention in such clear, concise, and exact language as to enable others skilled in the art to use the same, I claim as my invention and desire to secure by Letters Patent the following:

1. An orchard heater comprising a heater body adapted to be supported above the ground, said heaterbod-y having an aperture for primary air centrally located in its bottom, an open helical vaporizer so positioned within the heater body that the primary air admitted through the bottom of the heater mixes with thevolatilized fuel from the vaporizer, means for supplying liquid fuel to said vaporizer, a stack comprising two frusto-conical sections, each section having louvers around its periphery, said sections being fitted together at their large ends, the stack being centrally ositioned on the heater body and adapted to receive the mixture of primary air and fuel vapors from the heater body and to promote the burning of said mixture in the stack in the presence of secondary air admitted through the louvers positioned around the peripheries of the stack sections.

2. An orchard heater comprising a heater body adapted to be supported above the ground, said heater body having an aperture for primary air centrally located in the bottom thereof, an open helical vaporizer so positioned within the heater body that the primary air admitted through the bottom of the heater mixes with the volatilized fuel from the vaporizer, means for supplying liquid fuel to said vaporizer, and a louvered stack positioned on the heater body and adapted to receive the mixture of primary air and fuel vapors from the heater body and to admit secondary air to promote combustion of said mixture.

3. An orchard heater comprising a heater body, a fuel vaporizer positioned within said heater body, said vaporizer having an upper and a lower end and being adapted .toreceive liquid fuel and to discharge liquid fuel at the lower end, means for supplying liquid fuel to said vaporizer, a Wick positioned within the heater body beneath the lower end of the said fuel vaporizer to receive liquid therefrom, said wick being adapted to maintain a flame within said heater body below said fuel vaporizer and to ignite the fuel upon said fuel vaporizer, said heater body having a ort therein immediately adjacent said wick, said port being adapted to admit a draft of air over said wick to extinguish the flame thereon, a gate adjacent said port and adapted in a first position to baflle the flow of air away from the wick' and adapted in a second position out of alinement with said opening to permit air to flow directly over said wick to extinguish the flame, and heat responsive operating means attached to said gate which is adapted when heated to move the gate from its bafiling position to a non-baffling position.

4. An orchard heater of the drip type comprising a heater body having an air inlet centrally located in its bottom, a neck at the top of the heater body, a stack on said neck, said stack having louvers remote from the neck, a helical trough-like vaporizer between said inlet and said neck and coaxial with both, the diameter of said vaporizer being intermediate between the diameters of the inlet and the neck, so that the air from the inlet passes up through said vaporizer to the stack to cause combustion to occur mainly above said heater body and to expose fuel in the vaporizer effectively to the heat of such combustion, and means to feed liquid fuel to the upper end of the vaporizer.

5. An orchard heater of the drip type comprising a heater body, an inclined vaporizing trough in said body, means for feeding fuel to said trough adjacent its upper end, said heater body having a port near the bottom thereof, a Wick adjacent said port and positioned to receive the fuel dripping from the lower end of said vaporizing trough, a gate normally positioned between said port and said wick and baffling air flowing from said port toward the wick, and heat responsive means for fully opening said gate to admit a draft of air for extinguishing the flame of said wick after the fuel in the trough is ignited.

JOHN H. MCCRACKEN. 

